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Telephony, intercoms. Schemes, articles, descriptions

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Telephony, intercoms

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Connecting to the antenna of several TV (VHF) receivers



Section Television antennas. On fig. 1 shows antenna matching schemes with several receivers: VHF radios and TVs. The connection to the antenna is made using a standard 75 ohm coaxial cable. Antenna matching with several radio receivers is possible both with the help of fairly simple resistive dividers, and with the help of fairly complex circuits that use RF transformers, RF inductors, etc. ... >>

144 MHz Direct Conversion Receiver



Section Radio reception. The receiver is designed to operate in the range of 144-146 MHz. The circuits operating at frequencies above 100 MHz have a somewhat unusual appearance. These are quarter-wave resonators shortened by capacitance, curved to reduce dimensions. The design of the contours is clear from Fig. 2 ... >>

Technical characteristics of protective and disconnecting devices for mobile and portable current collectors



Electrical section. Protective disconnecting devices are designed to protect against electric shock people working with AC electrical installations. Currently, a large number of protective shutdown schemes have been developed. In networks with grounded and isolated neutral, it is possible to use protective shutdown devices of the ZOUP-25 type, designed for a consumer current of up to 25 A at a voltage of 380 V, the protection setting is 10 mA, the shutdown time is 0,05 s, the weight is 4,5 kg . When working with power tools of single-phase current with a total power of 0,5 kW at 220 V, ZOU-1 protective shutdown devices are used. For electric welding, the device of the USNT-4 type is the most promising. When connecting a three-phase motor to a single-phase network using capacitors, it must be taken into account that the rated voltage of capacitors of the KBG-MN and BGT types is given for their operation at direct current ... >>

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Articles on telephony, intercoms

Articles on telephony, intercoms; diagrams of telephony devices, intercoms; descriptions of telephony devices, intercoms: 168 articles

 


 

Latest news of science and technology, new electronics:

Using Apple Vision Pro during surgery 16.03.2024

The medical team at Cromwell Hospital in London used Apple Vision Pro for the first time during two spinal surgeries. This event confirms the headset's potential as a medical tool that will change the way surgical practice is performed. Although the doctors themselves did not use Vision Pro, the operating room nurse worked with virtual reality using glasses while preparing and performing procedures. The headset made it possible to view virtual screens in the operating room, select instruments and monitor the progress of the operation. Software developed by eXeX, a company that specializes in creating artificial intelligence-based applications for surgery, has significantly improved the patient care process. Using Apple Vision Pro opens up new opportunities for developing healthcare applications such as clinical education, surgical planning, training and medical imaging. Implementation of Apple Vision Pro in the medical industry ... >>

Carbon storage in the North Sea 16.03.2024

Norwegian Energy Minister Terje Åsland has announced the launch of the Longship project, which aims to create a central carbon dioxide storage facility in the North Sea. This ambitious project is valued at $2,6 billion and aims to apply CCS (carbon capture and storage) technology to mitigate the impact of climate change. Norway already has experience in CCS, thanks to the successful Sleipner and Snohvit projects, and is now looking to increase the amount of carbon sealed beneath the seabed. Longship's plan calls for capacity to capture and store 1,5 million tons of carbon annually over 25 years. Despite the positive outlook, there are concerns about the long-term consequences of such storage. However, proponents of the project argue that offshore carbon storage has a number of advantages, including minimal environmental impact. The Longship project is carried out with the participation of Equinor, Shell and TotalEnergies through the joint venture Northern Li ... >>

Mini-organs grown from human amniotic fluid 15.03.2024

An international team of scientists led by Professor Fan Xiulin from Zhejiang University has developed a unique method of growing mini-organs from cells found in human amniotic fluid. This significant medical breakthrough could lead to improved diagnosis and treatment of congenital diseases. The organoids, which are three-dimensional cellular structures that mimic organs on a smaller scale, were grown from lung, kidney and small intestine cells found in amniotic fluid. This method opens up new possibilities for studying various fetal conditions and may be the key to early diagnosis and treatment of birth defects. Although no treatment has yet been attempted, the scientists hope their research will help combat the serious congenital diseases that affect millions of newborns each year. This breakthrough could change medical interventions by making it possible to diagnose and treat congenital diseases. ... >>

Random news from the Archive

Samsung 12" Tablets 07.01.2014

Samsung has announced two tablets with a screen size of 12,2 inches. Samsung Galaxy Note Pro 12.2 and Samsung Galaxy Tab Pro 12.2 introduced. The devices are similar in design and features. The difference lies in the Note Pro 12.2's S Pen, which you can use to draw on the screen.

The screen in both models is made using LCD technology and has a resolution of 2560 x 1600 pixels, with a resolution of 247 ppi. Both models are equipped with a 9500 mAh battery, an 8 MP main camera and a 2 MP front camera.

Depending on the configuration, both Galaxy Note Pro 12.2 and Galaxy Tab Pro 12.2 can be equipped with an LTE communication module. This configuration is equipped with a Qualcomm Snapdragon 800 processor with a frequency of 2,3 GHz. The 3G (non-LTE) version is equipped with a Samsung Exynos 5 chip.

The choice will be offered models of tablets with built-in memory of 32 and 64 GB. The RAM capacity is 3 GB. Dimensions are 295,6 x 204 x 7,95 mm, weight - about 740 g.

In addition to the 12,2-inch models, Samsung introduced the Galaxy Tab Pro 8.4 and Galaxy Tab Pro 10.1 with 8,4-inch and 10,1-inch screens. The resolution of the displays in these tablets is also 2560 x 1600 pixels, which made it possible to obtain a pixel density of 359 and 298 ppi, respectively.

Depending on the configuration, devices can be equipped with Wi-Fi only or Wi-Fi and LTE. The battery capacity in the Galaxy Tab Pro 8.4 is 4800 mAh, in the Galaxy Tab Pro 10.1 - 8220 mAh.

All new devices run Android 4.4 KitKat. Samsung expects to start selling new products in the first quarter of 2014.

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